Effect of climatic ageing on properties of acrylic coatings

Three-layer acrylic coatings were deposited on steel substrates, aged at a climatic station for 1 year and studied for changes of their hardness, gloss, surface roughness, thermal stability and intensity of carbonyl groups band obsd. on the images of FTIR spectra. They revealed the oxidn. degree increase on the coating superficial layer. A decrease of oxidn. onset temp. as detd. by the thermal anal. method was noticed as well as a mass loss increas, detected by thermograwimetric anal. The interferometric microscopy revealed changes in topog. and roughness profile of the aged coatings whereas scanning electron microscopy showed craters, microcracks, etchings and silver cracks on their surface.